CN105910780B - A kind of rotary magnetic field fatigue exciting of the non-contact test specimen of controllable precise and vibration detecting device - Google Patents

Abstract

The invention provides an accurate and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measuring device, which includes a vibration-reducing and insulating fixture, a shock absorber, a dynamic balance device, a vibration exciter, an electromagnetic piezoelectric coupling vibration measuring sensor, a test stage, transmission and precise control device. This vibration excitation and vibration measurement device is suitable for the research on the vibration characteristics of rotating test pieces, especially wind power blades, engine, turbine blades, helicopter rotors, tail rotors and other blades; this device can simulate rotation separately and very realistically. The vibration fatigue state of similar test pieces under the conditions of 360° omnidirectional, different excitation force at the same rotation speed, different rotation speed at the same excitation force, and different excitation force at different rotation speeds; The vibration characteristic parameters related to the excitation force, vibration displacement, vibration velocity, vibration acceleration, etc. of the parts. In addition, the invention is also applicable to the vibration fatigue characteristic analysis of static test pieces.

Description

An Accurate and Controllable Non-contact Specimen Rotating Magnetic Field Fatigue Excitation and Vibration Measurement Device

technical field

The invention relates to a fatigue excitation and vibration measurement device, in particular to an accurate and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measurement device. The invention is particularly suitable as a test excitation and vibration measurement device for blades and rotor tail rotors.

Background technique

In the field of machinery, the phenomenon of vibration fatigue is ubiquitous. Vibration fatigue is very harmful to mechanical parts. If it is light, it will shorten the service life of the parts; if it is heavy, it will directly damage the parts and make them unusable; it will even endanger personal safety. Therefore, it is very necessary to study the vibration fatigue of mechanical parts, and its application value is huge. To study the vibration fatigue problem in the mechanical field, it is inseparable from the mechanical vibration device. The vibration excitation device in the mechanical field has many functions. This type of vibration excitation device can perform vibration test analysis, fatigue test analysis, material characteristic analysis of the test piece, life prediction analysis of the test piece, etc. for mechanical parts, mechanical equipment and other mechanical devices. A series of mechanical property analysis.

At present, there are many types of vibration excitation devices in the mechanical field. According to the contact relationship between the vibration source and the test piece, they include "contact" and "non-contact". Among them, there are many types of contact vibration source structures, specifically: electro-hydraulic, pneumatic, hydraulic and other structures; non-contact vibration source structures are mainly: electromagnetic structure.

The current contact fatigue excitation device has a relatively simple structure, low manufacturing cost, and can provide relatively stable excitation force. However, since the excitation force of the contact fatigue excitation device is provided by the mechanical structure, the magnitude and frequency of the excitation force provided to the specimen are limited, which makes the adjustable excitation frequency width and amplitude of the specimen small. As a result, the study of some mechanical properties of the specimen is limited. In addition, since the excitation structure is contact type, the test piece is in direct contact with the vibration source, which will change the structure of the test piece, affect the accuracy of the test results, and have an additional impact on the test.

In the current non-contact fatigue vibration device, the vibration source is provided by an electromagnet, and the vibration force is provided by an electromagnetic force, which is convenient to control. The size and frequency of the excitation force can be adjusted more conveniently, and the adjustable excitation frequency range of the test piece is very large, which is conducive to more comprehensive research on the mechanical characteristics of the test piece. In addition, since the excitation structure is non-contact, the test piece is not in direct contact with the vibration source, thus ensuring the structural integrity of the test piece and making the test results more accurate.

However, most of the current non-contact fatigue vibration excitation devices are fixed specimens; however, there are very few fatigue excitation devices suitable for rotating specimens. In particular, there are fewer fatigue excitation devices for studying wind power blades, engine, turbine blades, helicopter rotors, tail rotors, etc. in the rotating state. In addition, the use of wired sensors for vibration measurement of rotating specimens will increase the complexity of the test device. The fatigue vibration test is a difficult point in the field of vibration testing. Currently, there are few devices for testing the vibration characteristics of rotating specimens.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned technical problems, to provide a kind of accurate and controllable non-contact test piece rotary magnetic field fatigue excitation and vibration measuring device, which is mainly suitable for rotating test pieces, especially for rotating blades (wind power blades, Engine, turbine blade, helicopter rotor, tail rotor, etc.) vibration characteristics research, but also applicable to the vibration fatigue characteristics of static test pieces.

The technical solution adopted to achieve the purpose of the present invention is as follows, a precise controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measurement device, including vibration-damping insulation fixtures, shock absorbers, dynamic balance devices, vibration excitation Devices, electromagnetic piezoelectric coupling vibration sensors, test benches, transmission devices and precise control devices.

An electromagnet support frame is installed on the table of the test bench. The electromagnet support frame is provided with a vibration exciter clamping platform and an electromagnetic piezoelectric coupling vibration measuring sensor clamping platform.

The vibrator is an electromagnet with a hollow cylindrical iron core. The electromagnetic piezoelectric coupling vibration measuring sensor includes elastic thin steel sheet, piezoelectric ceramic sheet, piezoelectric processor, compression spring II and pressure sensor. The piezoelectric ceramic sheet is bonded to the lower surface of the elastic thin steel sheet. The piezoelectric processor is connected to the lower surface of the piezoelectric ceramic sheet. The elastic thin steel sheet, the piezoelectric ceramic sheet and the piezoelectric processor each have a vertical through hole in the center.

The vibrator is clamped on the electromagnet fixture. A compression spring II is placed in the hole of the electromagnet fixture on the electromagnet fixture, and a layer of non-magnetic material is plated on the surface of the compression spring II, and the relevant mechanical values measured by the piezoelectric sensor due to the magnetic force generated by the magnetic field on the compression spring II are removed imprecise effects. The flange bolt IV first passes through the ring-shaped pressure sensor, then passes through the compression spring II, the electromagnet clamp hole and the bolt hole of the vibrator clamping platform in sequence, and finally the threaded shaft section of the flange bolt IV is fixed on the vibrator Clamp the platform bolt holes. The compression spring II is in a slightly compressed state by the pre-pressure, the lower end is in constant contact with the stepped surface of the stepped hole I, and the upper end is also in constant contact with the pressure sensor. The electromagnet clamp is not fixedly connected with the clamping platform of the vibrator, and the electromagnet and the compression spring II can move axially on the smooth shaft section of the flange bolt IV.

The elastic thin steel sheet is located below the vibrator. The elastic thin steel sheet is fixed on the clamping platform of the electromagnetic piezoelectric coupling vibration measuring sensor through bolts. The axes of the through holes in the centers of the vibrator, the elastic thin steel sheet, the piezoelectric ceramic sheet and the piezoelectric processor are on the same straight line, so that the output shaft of the transmission device passes through the upper end of the vibrator from bottom to top. out.

The upper end of the output shaft is connected with a self-locking screw rod. A shock absorber is installed on the upper end of the self-locking screw. A vibration-damping insulation clamp is installed on the shock absorber. There is a cylindrical clamp joint on the vibration-damping insulating clamp. The clamp joint has a thread for connecting the shock absorber.

The shock absorber includes an upper elastic steel ring, a lower elastic steel ring, a steel ring connector, a screw joint and a damping spring I.

The screw joint is cylindrical, and a threaded hole matched with the self-locking screw is opened on its axis. There are four raised circular frustums on the circumferential side of the screw joint. The four circular platforms are arranged opposite to each other two by two in the orthogonal direction. A threaded hole is opened on the axis of each round platform, and the threaded hole radially penetrates the side wall of the screw joint.

The upper elastic steel ring is provided with four radially penetrating threaded holes, and these four threaded holes are opposite to each other in the orthogonal direction. The lower elastic steel ring is provided with several axially penetrating stepped holes, and its side wall is also provided with two threaded connection holes matched with the clamp joint and arranged symmetrically. The steel ring connector is composed of a bottom plate and an ear seat plate. The lug plate is vertically connected to the base plate, wherein the lug plate is provided with a through hole penetrating transversely, and the base plate is provided with two through holes vertically penetrating.

The screw joint is located in the inner cavity of the upper elastic steel ring, and the four circular platforms on it correspond to the four threaded holes on the upper elastic steel ring one by one. The outer side of the upper elastic steel ring is connected with four steel ring connectors. Flange bolts I pass through the through hole on the lug plate of the steel ring connector, the threaded hole of the upper elastic steel ring and the threaded hole on the axis of the circular table in turn, and they are fixed together.

The lower elastic steel ring is connected below the upper elastic steel ring through a steel ring connector. The damping spring I is placed in the stepped hole of the lower elastic steel ring. The flange bolt II passes through the through hole on the bottom plate of the steel ring connector, the vibration damping spring I and the stepped hole on the lower elastic steel ring in sequence, and they are fixedly connected together. The lower end of the damping spring I is in contact with the stepped surface of the stepped hole, and the upper end is in contact with the (bottom plate) lower surface of the steel ring connector.

Two vibration-damping insulating clamps are symmetrically installed on both sides of the lower elastic steel ring. One of the vibration-damping and insulating fixtures is equipped with a test piece, and the other vibration-damping and insulating fixture is equipped with a dynamic balance device.

The precise control device is used to adjust the distance between the test piece and the exciter, the rotational speed of the output shaft and the current of the exciter through computer analysis and processing.

Further, the vibration-damping insulation clamp includes a lower insulating splint, an upper insulating splint and a vibration-damping spring III. The clamp joint connects the sides of the lower insulating splint. The damping spring III is placed in the bolt hole of the test piece. The bolts pass through the upper insulating splint, damping spring III, the test piece and the lower insulating splint in turn, and the test piece is clamped between the upper and lower insulating plates.

Further, the transmission device also includes a driven gear, a driving gear, a driven shaft, a driving shaft, a shaft coupling and a steplessly adjustable AC motor. The output end of the stepless speed-regulating AC motor is connected with the drive shaft through a shaft coupling. A drive gear is installed on the drive shaft. A driven gear is installed on the driven shaft. The driven gear meshes with the driving gear. The driven shaft is connected with the output shaft.

Further, the dynamic balance device includes a balance piece of non-magnetic material (if it is a magnetic material, a thin layer of non-magnetic material can be plated on the periphery), and this balance piece is symmetrical to the axis of the output shaft of the test piece. The material, size, shape, and clamping method of the balance piece are consistent with those of the test piece.

Further, the outer diameter of the iron core of the vibrator is larger than the length of the test piece, and the inner diameter is larger than the diameter of the output shaft.

It should be noted that the precise control device of the present invention is divided into three modules: precise control of distance, precise control of rotational speed, and precise control of exciting force. Accurate distance control is to adjust the relative position of self-locking screw and screw joint when in use, so as to accurately adjust the distance between the test piece and the vibration source, and then indirectly change the excitation force on the test piece. Accurate control of the speed is mainly to adjust the speed of the speed-adjustable AC motor through the computer, and then reflect it to the speed of the test piece through the transmission of the coupling and the gear. The precise control of the exciting force mainly uses a computer and a current controller to directly and accurately control the magnitude and direction of the exciting force on the specimen by adjusting the magnitude and direction of the coil current of the electromagnet.

The present invention has the following advantages:

1. The present invention has a wide range of applicable objects. It is not only suitable for rotating test pieces, especially blades (wind turbine blades, engine blades, turbine blades, helicopter rotors, tail rotors, etc.); at the same time, it is also suitable for stationary test pieces. In addition, the material of the test piece can be either magnetic material or non-magnetic material; for non-magnetic material, it is only necessary to coat a thin layer of magnetic material on the surface of the test piece, because what the present invention involves is the vibration fatigue of the test piece. The purpose of the test is to study the vibration fatigue characteristics of the test piece in the process of vibration and fatigue failure. Plating a thin layer of material on the surface of the non-magnetic material has little effect on the overall results of the test and can be ignored.

2. The test reliability of the present invention is strong. The vibration source is an electromagnet, and the magnetic field force is used as the exciting force. The test piece and the vibration source are non-contact, not contact, so that the original structure of the test piece is not changed, and the boundary conditions of the structure are not changed. Therefore, the structural integrity of the test piece is good; in addition, the distance adjustment between the test piece and the vibration source is realized by a self-locking screw, which is accurate and reliable; moreover, because the screw has a self-locking function, the test piece and the vibration source The distance between the vibration sources will not change due to the vibration of the test piece and the rotation of the output shaft; so the test results are stable and reliable.

3. The present invention has strong controllability. First of all, the rotational speed of the specimen can be changed at any time according to the actual working conditions of the specimen. The adjustment range of the rotational speed of the specimen is very wide, which can realize the rotation of the specimen at different rotational speeds. Therefore, the rotational speed adjustment of the specimen is not only convenient but also accurate and reliable. . Second, the excitation force is regulated in two ways. First, indirect regulation: it is realized indirectly by regulating the distance between the test piece and the vibration source. Specifically, it is adjusted by the screw, because the screw is a precision transmission device, and the adjustment accuracy of the distance is good; the self-locking screw indirectly adjusts the excitation force of the test piece through the adjustment of the distance. Second, direct control: realized by computer, current controller, and exciter, by controlling the magnitude of the alternating current in the electromagnet to generate an alternating magnetic field, thereby generating an alternating excitation force; in addition, The adjustable frequency range of the exciting force is very large, which can make the test piece produce corresponding exciting effects in a wide range of exciting frequencies; at the same time, it can also quickly make the test piece reach the state of resonance fatigue, which is conducive to accelerating the fatigue of the test piece , and shorten the test time for studying the vibration fatigue process of the specimen.

4. The vibration measuring structure of the present invention is ingenious. Not only the vibration excitation device is designed, but also the vibration test device of the rotating test piece is designed. The test device involved is an electromagnetic piezoelectric coupling vibration sensor, which realizes the "wireless vibration measurement" of the rotating test piece. The electromagnet moves up and down on the flange bolts, and the distance between the electromagnet and the elastic thin steel sheet changes, so that the magnetic force between the electromagnet and the steel sheet changes accordingly, so that the elastic thin steel sheet is deformed, and then bonded The piezoelectric ceramic sheet on the elastic thin steel sheet is also deformed. Due to the piezoelectric effect, the piezoelectric ceramic sheet will generate a changing current, and then indirectly measure the vibration of the test piece through the piezoelectric processor, current amplifier and computer. Velocity, vibration acceleration, vibration displacement and other related vibration characteristic parameters; it solves the problem of increasing the complexity of the test device by using wired sensors for vibration measurement of rotating test pieces, thus realizing the "wireless vibration measurement" of rotating test pieces. In addition, the electromagnet in the vibration testing device is shared with the electromagnet of the vibration source, that is, the electromagnet involved in the present invention is used for both excitation and vibration measurement, and serves as a function in the two structures, which makes the excitation The vibration structure and the vibration measurement structure are more compact, and it is also easier to control the excitation and vibration measurement structures.

5. The experiment simulation of the present invention is strong. The vibration excitation device involved in the invention can very realistically simulate the vibration state of the rotating test piece in the actual working environment. The excitation device can make the specimen be subjected to the magnetic field force of equal strength at the same time within the range of 360°. The magnetic field force is an alternating force whose magnitude and direction can change with time. Moreover, the excitation device can provide the test piece with the vibration fatigue state under the conditions of the same speed and different exciting force, the same exciting force and different speed, and different speed and different exciting force, which is very convenient to make three identical test pieces in The comparative fatigue test under three different vibration conditions can more comprehensively study the vibration characteristics of the specimen in the vibration fatigue process. Through the provided vibration test device, relevant vibration characteristic parameters such as the excitation force, vibration displacement, vibration velocity, and vibration acceleration of the test piece can be monitored at all times. In addition, the vibration process and testing process of the test piece are monitored and regulated by the computer, so that the test piece can be regulated and monitored in real time from the beginning of vibration, to resonance, to crack growth and finally to fracture, etc. vibration fatigue failure process.

6. A damping device, i.e. a shock absorber, is added to the vibration excitation device of the present invention. The purpose of adding a shock absorber is to isolate the vibration of the test piece from the output shaft as much as possible, so that the output shaft does not vibrate due to the vibration of the test piece, that is, to avoid the resonance frequency of the output shaft; at the same time, in the insulating fixture The vibration damping spring III is added to ensure that the vibration exciter components such as insulating fixtures and shock absorbers will not resonate when the specimen undergoes vibration fatigue, so as to ensure the normal progress of the test.

7. A dynamic balance device is also added to the vibration excitation device of the present invention. Because when the test piece vibrates in the rotating state, if the balance piece is not installed on the symmetrical part of the test piece about the axis of the output shaft, the test piece will have a dynamic unbalance problem, especially when the test piece rotates at a high speed. The dynamic imbalance will be very obvious, which will greatly affect the test results and even make the test impossible, so it is necessary to add a dynamic balance device.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the present invention (power supply, computer, current amplifier and controller are not shown).

Fig. 2 is a structural schematic diagram of the vibration-damping insulating fixture.

Fig. 3 is a schematic diagram of the structure of the shock absorber.

Fig. 4 is a disassembled schematic diagram of the shock absorber structure.

Figure 5 is a schematic diagram of the connection of the shock absorber, the vibration-damping insulating fixture, the dynamic balancing device, and the test piece.

Figure 6 is a schematic diagram of the structure of the exciter.

Fig. 7 is a disassembled schematic diagram of the structure of the electromagnetic piezoelectric coupling vibration measuring sensor.

Fig. 8 is a schematic diagram of the connection of the exciter, the electromagnetic piezoelectric coupling vibration measuring sensor, and the electromagnet support frame.

Figure 9 is a top view of the electromagnet fixture.

Fig. 10 is a cross-sectional view at A-A in Fig. 9 .

Fig. 11 is a schematic diagram of the elastic connection structure of the electromagnet clamp.

Fig. 12 is a schematic diagram of the principle of the exciter.

Figure 13 is a schematic diagram of the force of the exciter.

Figure 14 is a schematic diagram of the force of the test piece.

Fig. 15 is a schematic diagram of the principle of the present invention.

In the figure: test piece 1, vibration damping insulation fixture 2, shock absorber 3, dynamic balance device 4, self-locking screw rod 5, output shaft 6, vibration exciter 7, electromagnetic piezoelectric coupling vibration measuring sensor 8, vibration exciter Clamping platform 9, clamping platform bolt hole 901, electromagnetic piezoelectric coupling vibration sensor clamping platform 10, electromagnet support frame 11, outlet hole 12, electromagnet support fixture 13, test bench 14, driven gear 15, drive Gear 16, driven shaft 1701, driving shaft 1702, coupling 18, stepless speed regulation AC motor 19, motor clamp 20, motor outlet hole 21, lower insulating splint 22, upper insulating splint 23, bolt 24, damping spring Ⅲ25, fixture joint 26, gasket 27, nut 28, lower elastic steel ring 29, upper elastic steel ring 30, screw joint 31, round table 3101, damping spring I32, nut with pad 33, steel ring connector 34, method Flange bolt Ⅰ35, threaded connection hole 36, flange bolt Ⅱ37, electromagnet 38, electromagnet clamp 39, flange bolt Ⅲ40, hollow hole 41, electromagnet clamp hole 42, stepped hole Ⅰ4201, stepped hole Ⅱ4202, nut with pad 43 , elastic thin steel sheet 44, piezoelectric ceramic sheet 45, piezoelectric processor 46, compression spring II 47, flange bolt IV 48, smooth shaft section 4801 of flange bolt IV, threaded shaft section 4802 of flange bolt IV, pressure sensor 49. Bolt 50.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but it should not be understood that the scope of the subject matter of the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various replacements and changes made according to common technical knowledge and conventional means in this field shall be included in the protection scope of the present invention.

Example 1:

This embodiment is aimed at rotating specimens.

A precise and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measurement device, including vibration-reducing and insulating fixture 2, vibration absorber 3, dynamic balance device 4, vibration exciter 7, electromagnetic piezoelectric coupling vibration measurement sensor 8 , Test bench 14, transmission device and precise control device.

Referring to FIG. 1 , an electromagnet support frame 11 is installed on the table of the test bench 14 . The electromagnet support frame 11 is U-shaped, and a through hole is provided in the center of its bottom plate, and a vibration exciter clamping platform 9 and an electromagnetic piezoelectric coupling vibration measuring sensor clamping platform 10 are provided on the inner walls of its two side plates.

First refer to Figure 6 to Figure 11, the part of the electromagnetic piezoelectric coupling vibration measuring sensor device:

The main part of the vibrator 7 is a hollow cylindrical iron core electromagnet 38 . The electromagnet 38 is composed of a hollow cylindrical iron core and an enameled wire. The cylindrical iron core has a hollow hole 41 for coaxial cooperation between the electromagnet 38 and the output shaft 6 .

The electromagnetic piezoelectric coupling vibration measuring sensor 8 includes an elastic thin steel sheet 44 , a piezoelectric ceramic sheet 45 , a piezoelectric processor 46 , a compression spring II 47 and a pressure sensor 49 . The piezoelectric ceramic sheet 45 is bonded to the lower surface of the elastic thin steel sheet 44 by a strong adhesive. The piezoelectric processor 46 is connected to the lower surface of the piezoelectric ceramic sheet 45 . Each of the elastic thin steel sheet 44 , the piezoelectric ceramic sheet 45 and the piezoelectric processor 46 has a vertical through hole in its center.

Referring to FIG. 9 to FIG. 11 , the electromagnet 38 of the vibrator 7 is fixed and clamped on the electromagnet fixture 39 through the flange bolt III 40 and the washer nut 43 . Wherein the electromagnet 38 is used for the wire that connects the power supply to pass through from the outlet hole 12 . A less rigid compression spring II 47 is placed in the clamp hole 42 of the electromagnet (the clamp hole is a smooth hole, not a threaded hole). The electromagnet fixture hole 42 is composed of two sections, the stepped hole I 4201 and the stepped hole II 4202 , wherein the radius of the stepped hole I 4201 is greater than the radius of the stepped hole II 4202 .

Flange bolt IV 48 first passes through the ring-shaped pressure sensor 49, then passes through the compression spring II 47, the electromagnet clamp hole 42 and the clamping platform bolt hole 901 of the exciter clamping platform 9, and finally the threaded shaft of the flange bolt IV The segment 4802 is secured in the bolt hole 901 of the clamping platform. The compression spring II47 is in a slightly compressed state by the pre-pressure, the lower end is always in contact with the stepped surface of the stepped hole I4201, and the upper end is also in constant contact with the pressure sensor 49. The upper surface of the pressure sensor 49 is in close contact with the bolt head of the flange bolt IV48. The compression spring II 47 can move up and down on the smooth shaft section 4801 of the flange bolt IV together with the electromagnet clamp 39 . The electromagnet clamp 39 is connected with the electromagnet 38, so that the electromagnet 38 can move up and down on the smooth shaft section 4801 of the flange bolt IV together with the compression spring II47.

The outer diameter of the compression spring II47 is slightly smaller than the diameter of the stepped hole I4201, so that the compression spring II47 is in friction-free contact with the hole wall, so that the spring can move up and down freely; similarly, the inner diameter of the compression spring II47 is slightly larger than that of the flange bolt IV The diameter of the smooth section 4801 is such that the compression spring II 47 can make frictionless contact on the flange bolt IV 48, thereby enabling the spring to move freely up and down.

The elastic thin steel sheet 44 is located below the vibrator 7 . The elastic thin steel sheet 44 is fixed on the clamping platform 10 of the electromagnetic piezoelectric coupling vibration measuring sensor by bolts 50 . The axes of the through holes in the respective centers of the vibrator 7, the elastic thin steel sheet 44, the piezoelectric ceramic sheet 45 and the piezoelectric processor 46 are located on the same straight line, so that the output shaft 6 of the transmission device can move from the bottom to the top. The upper end of vibrator 7 passes out.

The connection of the above elements constitutes an electromagnetic piezoelectric coupling vibration measuring sensor device. Among them, the electromagnetic piezoelectric coupling sensor 8 and the exciter 7 share an electromagnet 38, which not only makes the excitation structure and the vibration measurement structure more compact, but also facilitates the computer to control the vibration excitation and vibration measurement structures.

See Figure 1, transmission part:

The transmission device also includes a driven gear 15 , a driving gear 16 , a driven shaft 1701 , a driving shaft 1702 , a shaft coupling 18 and a steplessly adjustable AC motor 19 . The output end of the stepless speed-regulating AC motor 19 is connected to the drive shaft 1702 through a coupling 18 . The driving gear 16 is installed on the driving shaft 1702 . The driven shaft 1701 and the driving shaft 1702 have corresponding axial positioning in the axial direction to prevent the gears from moving axially, thereby realizing the smooth transmission between the driving shaft 1702 and the driven shaft 1701 . The driven gear 15 is installed on the driven shaft 1701 . The driven gear 15 meshes with the driving gear 16 . The driven shaft 1701 is connected with the output shaft 6 . The gear transmission is selected because the gear transmission is stable and the transmission ratio is accurate. In addition to meeting the requirements of low and medium speeds, it can also meet the requirements of high speeds, so the gear transmission is selected. The stepless speed regulation AC motor 19 is fixed on the test bench 14 through the motor fixture 20, and the speed of the stepless speed regulation AC motor 19 is regulated by a computer, so that the rotary motion of the test piece 1 is finally realized, which is very realistically simulated The rotation of the test piece 1 in the actual working speed is realized; at the same time, the purpose of precise and convenient control of the speed of the test piece by the computer is realized. Wherein, the motor wire outlet hole 21 on the test bench 14 is used for the entry and exit of motor control lines.

The upper end of the output shaft 6 has a hollow part, which is engraved with an internal thread, which is used for threaded connection with the threaded shaft of the self-locking screw rod 5, and the threaded shaft is precisely driven through the internal threaded hole, thereby realizing precise control of the test piece. The displacement in the axial direction of the output shaft 6 realizes the adjustment of the distance between the test piece 1 and the vibrator 7 . In addition, since the self-locking screw rod 5 has a self-locking function and its joint part is fixedly connected to the output shaft 6 , the self-locking screw rod 5 will rotate together with the output shaft 6 . The upper end of the self-locking screw rod 5 is equipped with a shock absorber 3 .

See Figure 2 to Figure 5, the part of the clamping and vibration damping device composed of the test piece, insulating fixture, dynamic balance device and shock absorber:

The shock absorber 3 is installed with a vibration-damping insulation clamp 2 . A cylindrical clamp joint 26 is provided on the vibration-damping insulation clamp 2 . The clamp joint 26 has a thread for connecting the shock absorber 3 .

3 and 4, the shock absorber 3 includes an upper elastic steel ring 30, a lower elastic steel ring 29, a steel ring connector 34, a screw joint 31 and a damping spring I32. The screw joint 31 is cylindrical, and a threaded hole matched with the self-locking screw 5 is formed on its axis. There are four raised circular platforms 3101 on the circumferential side of the screw joint 31 . The four circular platforms 3101 are arranged opposite to each other in the orthogonal direction. A threaded hole is opened on the axis of each round platform 3101 , and the threaded hole radially penetrates the side wall of the screw joint 31 .

The upper elastic steel ring 30 is provided with four radially penetrating threaded holes, and these four threaded holes are opposite to each other in the orthogonal direction. The lower elastic steel ring 29 is provided with eight axially penetrating stepped holes, and its side wall is also provided with two threaded connection holes 36 matched with the clamp joint 26 and arranged symmetrically. The steel ring connector 34 is composed of a bottom plate and an ear seat plate. The lug plate is vertically connected to the base plate, wherein the lug plate is provided with a through hole penetrating transversely, and the base plate is provided with two through holes vertically penetrating.

The screw joint 31 is located in the inner cavity of the upper elastic steel ring 30 , and the four circular platforms 3101 on it correspond to the four threaded holes on the upper elastic steel ring 30 one by one. The outer side of the upper elastic steel ring 30 is connected with four steel ring connectors 34 . The flange bolt I35 passes through the through hole on the lug plate of the steel ring connector 34, the threaded hole of the upper elastic steel ring 30 and the threaded hole on the axis of the round platform 3101 in sequence, and they are fixedly connected together.

The lower elastic steel ring 29 is connected below the upper elastic steel ring 30 through a steel ring connector 34 . The damping spring I32 is placed in the stepped hole of the lower elastic steel ring 29 . The flange bolt II 37 passes through the through hole on the bottom plate of the steel ring connector 34, the damping spring I 32 and the stepped hole on the lower elastic steel ring 29 in order to securely connect them together. The lower end of the damping spring I32 is in contact with the stepped surface of the stepped hole, and the upper end is in contact with the lower surface of the steel ring connector 34 (bottom plate).

Two vibration-damping insulating clamps 2 are installed symmetrically on both sides of the lower elastic steel ring 29 . A test piece 1 is clamped on one of the vibration-damping and insulating fixtures 2 , and a dynamic balance device 4 is clamped on the other vibration-damping and insulating fixture 2 . Wherein the vibration-damping insulation clamp 2 includes a lower insulating splint 22 , an upper insulating splint 23 and a vibration-damping spring III 25 . The clamp joint 26 is connected to the side of the lower insulating clamping plate 22 . The damping spring III25 is placed in the bolt hole of the test piece 1. Bolts 24 pass through the upper insulating splint 23, damping spring III 25, test piece 1 and lower insulating splint 22 in sequence, and the test piece 1 is clamped between the upper and lower insulating plates. Wherein the damping spring III25 is in a compressed state. The insulating splint is used to prevent the induced current generated by the test piece 1 from forming a circuit, which will affect the test results; the vibration generated by the test piece 1 will be transmitted through the fixture, which will affect the test results, so the vibration damping spring Ⅲ25 is used to weaken the vibration transmission Degree.

The structure of the shock absorber 3 is simple, symmetrical and ingeniously designed, and the eight damping springs I32 used symmetrically contact the lower elastic steel ring 29 and the upper elastic steel ring 30 indirectly, so that the damping effect is well achieved. In addition, there is a threaded hole in the axial direction of the screw joint 31, which is used to connect with the screw shaft of the self-locking screw 5. There are threaded connection holes 36 at the left and right ends of the lower elastic steel ring 29, wherein the right end threaded connection hole 36 is used to connect with the clamp joint 26 and the corresponding nut washer; the left end threaded connection hole 36 is used for connecting with the dynamic balance device 4 The dynamic balance device is used to balance the dynamic unbalance caused by rotating the test piece 1 during the test. In this way, the test piece, the insulating fixture, the shock absorber and the dynamic balance device are assembled together, and its structural schematic diagram is shown in Figure 5.

In this embodiment, the radius of the hollow hole 41 is slightly greater than the distance from the vibration-damping insulation fixture 2 to the centerline of the output shaft 6, and the purpose of this is to weaken the excitation degree of the vibration source to the shock absorber 3 and the vibration-damping insulation fixture 2, because The excitation object of the vibration source is the specimen 1.

The precise control device is used to adjust the distance between the test piece 1 and the vibrator 7 , the rotational speed of the output shaft 6 and the current of the vibrator 7 through computer analysis and processing.

Referring specifically to Fig. 12, the electromagnet 38 provides an alternating excitation force to the test piece 1: an alternating current is passed into the electromagnet 38 to generate an alternating magnetic field, and under the action of the magnetic field force, a vibration will occur between the magnetic field and the test piece 1. interaction, that is, the test piece 1 is affected by the exciting force; the magnitude, direction and frequency of the exciting force can change with time, and the exciting force is controlled by the current controller, and the current controller is connected with the computer. Through the computer, the current controller is controlled by the computer, so that the rotating test piece is subjected to the alternating exciting force in the direction of 360°, so that the vibration process of the test piece during the rotation process is realistically simulated.

Test principle:

The specific test principle of the present invention is as follows. With reference to Fig. 13 and Fig. 14, before passing the current to the exciter for testing, the compression spring II 47 is in a micro-pressure state through the pre-pressure, and its pre-pressure H ₀ (t) can pass The pressure sensor 49 measures, and the quality m of the vibrator can be known. After the test, the compression spring II47 is further compressed and deformed. The upper end of the compression spring II47 is always in contact with the pressure sensor 49, and the lower end is always in contact with the stepped surface of the stepped hole I4201. The pressure sensor 49 can measure the pressure of the compression spring II47 on the pressure sensor 49. H(t), because the action of the force is mutual, so the pressure I(t) of the compression spring II47 on the vibrator 7 is equal to the pressure H(t), and the direction is opposite to the direction of the pressure H(t). Its relationship is shown in (1). Since the compression spring II47 is in a slightly compressed state before the test, a preload H ₀ (t) is generated; the compression spring II47 is further deformed after the test and the elastic force F(t) is equal to I(t) and H ₀ (t), the direction is vertically downward.

The vibrator 7 moves up and down on the smooth shaft section 4801 of the flange bolt IV 48, and the distance between the electromagnet 38 and the elastic thin steel sheet 44 changes, so that the magnetic force between the vibrator 7 and the elastic thin steel sheet 44 changes with the change, so that the elastic thin steel sheet 44 is deformed, and then the piezoelectric ceramic sheet 45 bonded to the steel sheet is also deformed accordingly. Due to the piezoelectric effect, the piezoelectric ceramic sheet 45 will produce a changing current, and the current passes through The piezoelectric processor 46 and the current amplifier transmit the signal to the computer to measure the vibration acceleration a(t) of the vibrator. The stress model of the vibrator 7 can be reasonably simplified, and the schematic diagram of the force of the vibrator 7 is shown in FIG. 13 .

The vibrator 7 is subjected to three forces: the elastic force F(t) generated by the further deformation of the compression spring II47 after the test, its own gravity G and the force f(t). Because the mass m of the exciter 7 is known, the pre-pressure H ₀ (t) can be measured by the pressure sensor 49, and the pressure of the compression spring II 47 on the pressure sensor 49 can also be measured by the pressure sensor 49. The pressure I(t) of the device 7 can be obtained by the relation (1); the elastic force F(t) produced by the further deformation of the compression spring II47 after the test can be obtained by the formula (2), and the self-gravity G can be obtained by the formula It is calculated that the vibration acceleration a(t) of the exciter can be measured by the electromagnetic piezoelectric coupling vibration measuring sensor 8; then according to Newton's second law, and using relational expression (3), the vibration exciter 7 can be obtained with The force f(t) experienced by the change of time t. Its related relationship is as follows:

I(t)=-H(t) (1)

F(t)＝I(t)-H ₀ (t) (2)

f(t)-F(t)-G=ma(t) (3)

The mass m, the acceleration of gravity g, the measured vibration acceleration a(t), the preload H ₀ (t), the pressure H(t) of the compression spring II47 on the pressure sensor 49, the pressure of the compression spring II47 on the vibrator 7 I(t) and relational expressions (1), (2) and (3) are input into the computer, and the magnitude and direction of the force f(t) are calculated through the program, and the data are saved. Since the exciter and the test piece interact through the exciting force, according to Newton's third law, it can be known that the exciting force on the test piece is the force f(t). Then, the specimen is simplified into a cantilever beam, and the force diagram of the specimen is shown in Figure 14; according to the theoretical knowledge of the forced vibration of the cantilever beam under periodic excitation, Newton's second law, and the relationship (3), (4) , to find the vibration displacement u(t) of the specimen, the relationship (4) is as follows:

Where p is the mass density of the specimen, A is the cross-sectional area of the specimen, E is the elastic modulus of the specimen, I is the moment of inertia of the specimen on the neutral axis x, and f(t) is the Exciting force, u(t) is the vibration displacement of the specimen. Among them, it can be known from relational formulas (1), (2), (3) and (4): except the vibration displacement u(t), other parameters are known or can be obtained directly, so the relevant parameters and the corresponding Enter the relational expression into the computer, use MATLAB mathematical software to obtain the vibration displacement u(t) of the test piece, and then use the differential method to calculate the first and second derivatives of the vibration displacement u(t) of the test piece respectively, and then you can get The vibration velocity v(t) and vibration acceleration a(t) of the specimen at any moment. In this way, through the above steps, the vibration fatigue characteristic parameters such as the excitation force, vibration displacement, vibration velocity, and vibration acceleration of the specimen at any time can be accurately tested, and the excitation force, vibration displacement, and vibration velocity can be obtained respectively through the computer. , vibration acceleration and time fatigue characteristic curve, and then can monitor a series of continuous vibration states of the rotating test piece from normal to fatigue failure at all times, thus realizing the research on the vibration fatigue characteristics of the rotating test piece in the whole process.

Example 2:

This embodiment is aimed at static test pieces.

The implementation mode and principle of static test pieces are similar to those of rotating test pieces. Specifically, when the test piece is in a static state, the structure and working principle of the clamp, shock absorber, self-locking screw adjustment device and vibration exciter of the present invention are the same as those in the rotating state, and the control device and principle of the vibration source are also the same ; The difference is: cut off the power supply of the stepless speed-adjustable AC motor, so that the test piece is tested in a static state; and the object of the test is wider than that in the rotating state; in addition, the vibration measuring device can be different. In addition to the electromagnetic piezoelectric coupling sensor, the vibration device can also use a wired sensor to measure vibration.

Claims (5)

1. An accurate and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measurement device, characterized in that it includes a vibration-damping insulation fixture (2), a shock absorber (3), a dynamic balance device (4), an excitation vibrator (7), electromagnetic piezoelectric coupling vibration sensor (8), test bench (14), transmission device and precise control device; An electromagnet support frame (11) is installed on the test bench (14); the electromagnet support frame (11) is provided with a vibrator clamping platform (9) and an electromagnetic piezoelectric coupling vibration sensor clamping platform(10); The exciter (7) includes a hollow cylindrical iron core electromagnet; the electromagnetic piezoelectric coupling vibration sensor (8) includes elastic thin steel sheet (44), piezoelectric ceramic sheet (45), piezoelectric electric processor (46), compression spring II (47) and pressure sensor (49); the piezoelectric ceramic sheet (45) is bonded to the lower surface of the elastic thin steel sheet (44); the piezoelectric processor ( 46) connected to the lower surface of the piezoelectric ceramic sheet (45); the centers of the elastic thin steel sheet (44), the piezoelectric ceramic sheet (45) and the piezoelectric processor (46) each have a vertically penetrating through hole hole; The electromagnet of the exciter (7) is clamped on the electromagnet fixture (39); the compression spring II (47) is placed in the electromagnet fixture hole (42) on the electromagnet fixture (39); the flange Bolt IV (48) first passes through the ring-shaped pressure sensor (49), and then passes through the compression spring II (47), the electromagnet clamp hole (42) and the bolt hole of the clamping platform of the exciter clamping platform (9) in sequence (901), and finally the threaded shaft section (4802) of the flange bolt IV (48) is fixed in the bolt hole (901) of the clamping platform; the compression spring II (47) is in a slightly compressed state through the preload, and the lower end is in contact with the The stepped surface of the stepped hole I (4201) is always in contact, and the upper end is always in contact with the pressure sensor (49); The elastic thin steel sheet (44) is located below the vibrator (7); the elastic thin steel sheet (44) is fixed on the clamping platform (10) of the electromagnetic piezoelectric coupling vibration measuring sensor by bolts; The axes of the through holes in the center of the vibrator (7), elastic thin steel sheet (44), piezoelectric ceramic sheet (45) and piezoelectric processor (46) are on the same straight line for the output shaft (6) of the transmission device Pass through the upper end of the vibrator (7) from bottom to top; The upper end of the output shaft (6) is connected to the self-locking screw rod (5); the upper end of the self-locking screw rod (5) is installed with a shock absorber (3); the shock absorber (3) is installed with a vibration-damping insulation The clamp (2); the vibration-damping insulation clamp (2) has a cylindrical clamp joint (26); the clamp joint (26) has a thread for connecting the shock absorber (3); The shock absorber (3) includes an upper elastic steel ring (30), a lower elastic steel ring (29), a steel ring connector (34), a screw joint (31) and a damping spring I (32); The screw joint (31) is cylindrical, with a threaded hole on its axis for matching with the self-locking screw (5); there are four protrusions on the circumferential side of the screw joint (31) The four round tables (3101) are arranged opposite to each other in the orthogonal direction; each round table (3101) has a threaded hole on the axis, and the threaded hole radially penetrates through the screw joint (31) side wall; The upper elastic steel ring (30) has four radially penetrating threaded holes, and these four threaded holes are opposite to each other in the orthogonal direction; the lower elastic steel ring (29) has several axially penetrating holes. There are two threaded connection holes (36) arranged symmetrically with the fixture joint (26) on its side wall; the steel ring connector (34) is composed of a bottom plate and an ear seat plate; The ear seat plate is vertically connected to the bottom plate, wherein the ear seat plate is provided with a through-hole that penetrates horizontally, and the bottom plate is provided with two through-holes that penetrate vertically; The screw joint (31) is located in the inner cavity of the upper elastic steel ring (30), and the four circular platforms (3101) on it correspond to the four threaded holes on the upper elastic steel ring (30); The outer side of the upper elastic steel ring (30) is connected with four steel ring connectors (34); the flange bolt I (35) passes through the through hole on the lug plate of the steel ring connector (34) in turn, and the upper elastic steel ring (30) and the threaded hole on the axis of the round platform (3101) to connect them together; The lower elastic steel ring (29) is connected under the upper elastic steel ring (30) through the steel ring connector (34); the damping spring I (32) is placed in the stepped hole of the lower elastic steel ring (29) ; Flange bolt II (37) passes through the through hole on the bottom plate of the steel ring connector (34), the damping spring I (32) and the stepped hole on the lower elastic steel ring (29) in sequence, and they are fixedly connected to the Together; the lower end of the damping spring I (32) is in contact with the stepped surface of the stepped hole, and the upper end is in contact with the lower surface of the steel ring connector (34); Two vibration-damping insulation fixtures (2) are installed symmetrically on both sides of the lower elastic steel ring (29); one of the vibration-damping insulation fixtures (2) clamps the test piece (1) on top, and the other vibration-damping insulation fixture (2) clamps on the top Dynamic balancing device (4); The precise control device is used to adjust the distance between the test piece (1) and the exciter (7), the rotational speed of the output shaft (6) and the current of the exciter (7) through computer analysis and processing. 2. A precise and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measurement device according to claim 1, characterized in that: the vibration-damping insulation fixture (2) includes a lower insulating splint (22), The upper insulating splint (23) and damping spring III (25); the clamp joint (26) connects the side of the lower insulating splint (22); the damping spring III (25) is placed on the bolt of the test piece (1) In the hole; bolts pass through the upper insulating splint (23), damping spring III (25), test piece (1) and lower insulating splint (22) in sequence, and the test piece (1) is clamped between the upper and lower insulating plates between. 3. A precise and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measuring device according to claim 1, characterized in that: the transmission device also includes a driven gear (15), a driving gear (16 ), the driven shaft (1701), the driving shaft (1702), the coupling (18) and the stepless speed regulation AC motor (19); the output end of the stepless speed regulation AC motor (19) passes through the coupling (18) Connected with the driving shaft (1702); the driving gear (16) is installed on the driving shaft (1702); the driven gear (15) is installed on the driven shaft (1701); the driven gear (15 ) meshes with the driving gear (16); the driven shaft (1701) is connected with the output shaft (6). 4. A precise and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measuring device according to claim 1, characterized in that: the dynamic balancing device (4) includes a non-magnetic material balance piece, the The balance piece and the test piece (1) are symmetrical about the axis of the output shaft (6); the material, size, shape and clamping method of the balance piece are consistent with the test piece (1). 5. A precise and controllable non-contact test piece rotating magnetic field fatigue excitation and vibration measuring device according to claim 1, characterized in that: the outer diameter of the iron core of the vibrator (7) is larger than the test piece The length of (1), inner diameter is greater than the diameter of output shaft (6).